1. Technical Field
The present invention relates to an actuator, a manufacturing method of an actuator, a light scanner, and an image forming apparatus.
2. Related Art
As an actuator, an actuator using a structure forming a torsional vibrator has been known (for example, see Patent Document 1 (JP-A-2010-79243)).
For example, Patent Document 1 discloses a light deflector having a movable plate, a support frame (support part), a pair of elastic support parts (connection parts) that support the movable plate torsionally rotatable with respect to the support frame, each elastic support part including two bars (beam members).
The movable plate, the support frame, and the pair of elastic support parts are integrally formed by anisotropic etching of a silicon substrate with a principal surface formed by the (100) surface of silicon.
After masks having opening are respectively formed on both surfaces of the silicon substrate, the anisotropic etching is performed via the masks. The outer shapes of the cross-sections of the respective bars of the elastic support parts formed as above form parallelograms with pairs of sides along the (100) surface of silicon and pairs of sides along the (111) surface of silicon.
However, in related art, due to misalignment between the front and rear masks of the silicon substrate, level differences are respectively produced on the pair of side surfaces that should be formed by the (111) surface of the respective bars of the elastic support parts, and the level difference on one side surface and the level difference on the other side surface are located in the same position in the thickness direction of the silicon substrate. Accordingly, stress is easily concentrated on parts of the respective bars of the elastic support parts and breakage may be caused.